Help in looking over a Wiring Diagram - Car Second Battery and Accessories

[MichelleKiwi]

I brought a new car and want to wire a Dual Car Battery and Accessories.

I made this Wiring Diagram over the last week
I haven't bought most of the items yet, I've been looking at Aliexpress and this is cheapest / safest way I can see.

I want to self Jump start
I want to add a second 12V battery placed in the back of the vehicle, which isolated in both the back and the front
I want to install LED Fog lights
I want to control (Open/Close) the windows after the key is turned off for 15 mins afterwards

I want to install various LED Lights, A new Stereo, DVR cameras, USB and Cigarette Lighter Sockets
I want to install all the new items in the line above to be powered from either battery without affecting the factory wiring by using a timer relay set to 30 mins


Cable Sizes I'm planning of using:
2GA (Pos and Neg) between the two batteries
8GA to the 60A fuses / 80A Relays / 10 Way Fuse Box
12GA to 18GA after the 10 Way Fuse Box
18GA to 22GA to the coils of the Relays / Solenoids


View attachment New Car Drawing.pdf

Does anyone see a problem with this diagram?
Anyone think this is over or under engineering it?

Thanks

 

[MichelleKiwi]

Sorry, First Time Posting here, unable to post link, Photo is in higher resolution now.
I haven't used Microsoft Visio that much forgive any inconsistencies


View attachment New Car Drawing.pdf

 

[MichelleKiwi]

Anyone? Does anyone see a problem or something that could be improved?

Thank you

 

[Retired Tanker]

Anyone? Does anyone see a problem or something that could be improved?

Thank you

Remove the arrows in the links. They're confusing and are more suitable for data flow diagrams.

Use red for positive up to the first switch. Use black for ground from the load to the ground, but terminate in a grounding symbol as quickly as possible.

Use colors for identifying discreet circuits, but don't use plain red beyond the first switch. If you want to show the difference between switched and full time power, use a broken red line for the switched.

Try to get each length as short as possible. Power > fuse > switch > load > ground.

If you want to add physical layout (like grouping into a single fuse box) then draw a box around the group and label it in the corner. Putting "10 Way Direct Fuse Box" in the circuit is confusing.

 

[MichelleKiwi]

Thank you, That is helpful.

This is the first time I've created a diagram like this.

I'm planning on taking this to an auto electrician and getting them to help me put all this in.

I have a very basic knowledge of circuity and a cars electrical system
I took ideas from here using evldave "How to make a cheap isolated dual-battery setup for $50" great design and others from here and elsewhere
Thanks

 

[eli]

just some questions or comments. . .
1. Had you considered using a "SPOD"? They appear to be very well made & designed.
2. Had you considered completely isolating (exception being the ability to charge both batteries safely/independently) accessories circuit to keep all your factory systems operational in the event of a failure?

 

[MichelleKiwi]

just some questions or comments. . .
1. Had you considered using a "SPOD"? They appear to be very well made & designed.

I haven't heard the term SPOD before but from googling I think you are referring a set of switches within a panel.
I was thinking something similar but with individual switches drilled through the dash board, to control the roof lights

2. Had you considered completely isolating (exception being the ability to charge both batteries safely/independently) accessories circuit to keep all your factory systems operational in the event of a failure?

I think I have them isolated, except that when the accessories circuit is live, it energizes the relay and turns my wiring on.
Do you think I shouldn't do that? And have them completely isolated from each other?

 

[MichelleKiwi]

Revised Diagram



I've started to modify the diagram, I'll move the fog lights and the windows to another diagram as well.

Thanks

 

[Retired Tanker]

I've started to modify the diagram, I'll move the fog lights and the windows to another diagram as well.

Thanks

MUCH better!

I think it's a usable diagram, but if you wanted to clean it up just a bit more, move the physical descriptions out of the circuits. You go into great detail with diodes, but adding "fuse box" into the circuit without showing the internal specs (fuse capacity) makes it look clunky.

But, it is a lot cleaner than before.

 

[MichelleKiwi]

Thanks, It really should say "Factory Wiring & Fuses" I guess then. I'm not exactly sure how the factory wiring works from battery to (i.e.) ACC wire. So it really means I can't draw in what I don't know.

I wasn't going to play around with the factory wiring other than splicing in a couple of relays into it, as I know they only draw around 200mA each and shouldn't blow any fuses or short out and destroy the car.